How to let softbody assume default shape again
Alright figured it out myself, you need to tweak the goal damping value. Not too low and not too high.



Used a value of 1 for this one and it now looks exactly like the original. You can see that the original is also still there, since there's a small shading intersection where the green shines through on the right.

Small update: I only made a few tests but it seems that the scale of your softbody also influences if and how fast it can assume the default shape again: The bigger the better.